This is a collection of the Legal Theory Lexicon posts from Legal Theory Blog. A new entry appears each week on Sunday. The most recent posts appear on this page. To access older posts use the "Table of Contents" below. (Many of the Legal Theory Lexicon posts have benefitted from comments by Ken Simons of the Boston University School of Law.)

Sunday, June 13, 2004

Legal Theory Lexicon 040: Functional Explanation in Legal Theory

Introduction
In a prior installment of the Legal Theory Lexicon, we explored the difference between Positive and Normative Legal Theories. Positive legal theory attempts to explain and predict legal behavior, especially the content of legal rules. Normative legal theory makes claims about what those rules should be. This week's post is about an important and familiar concept in positive legal theory--the idea of a functional explanation.
Why do legal rules have the form and content that they do, in fact, have? One answer to this question is based on the idea that the function of a rule can be part of a causal explanation of the content of the rule. Why does corporations law limit the liability of stockholders? One kind of answer to that question might begin: "That rule is the way it is, because it serves the interest of the capitalist class." Or, "The rule is that way, because that is the efficient rule, and common law adjudication selects for efficient rules." In other words, the content of the rule is explained (causally) by the function the rule serves.The Idea of a Functionalist Explanation
Functionalist explanations are familiar to almost everyone, because of the important role they play in evolutionary biology. When we try to explain why an organism has a particular trait--why male peacock's have their feathers or why the elephants have trunks--we appeal to the function that the trait serves. Male peacock's have colorful feathers because that trait serves to attract female peacock's and hence the genes produce this trait are favored by evolution. Elephants have trunks, because they enable elephants to eat and drink more efficiently.
In biology, functionalist explanations are scientifically valid, because we understand the causal mechanism whereby function plays a causal role. That causal mechanism is evolution, of course, and we have a very good explanation for how evolution works in the form of genetics. DNA (plus a lot of other stuff) provides the precise causal mechanism by which evolution operates.Functionalist Explanation in the Social Sciences
Functionalist explanations are not limited to biology. Sociologists frequently explain social behavior on the basis of the social function that the behavior serves. Why does this group do a "rain dance"? Because the rain dance ritual serves to create social cohesion in times of stress. There is, however, a significance difference between functionalist explanation in biology and functionalist explanation in the social sciences. In biology, functionalist explanations are underwritten by a well-confirmed theory of the causal mechanism by which evolution functions. In social science, the causal mechanisms are murkier. What causal law explains how the social cohesion function of rain dances leads to their perpetuation across generations? Without an answer to questions like this, we have at least prima facie reason to be suspicious of functionalist explanations in the social sciences. This suspicion is enhanced because functionalist explanations can easily become nonfalsifiabile. In the case of biology, because evolutionary theory is well confirmed, we more or less know in advance that some functionalist explanation has got to be right--the question is which functionalist explanation is correct. In the case of social science, there is no well-confirmed general theory of social evolution, so it isn't necessarily the case that there is always a true functionalist explanation for any given social behavior.Functionalist Explanations in Legal Theory
And that brings us to law. Functionalist explanations are frequently invoked in positive legal theory. That is, when we ask the question, "Why does the law have such and such content?", the answer frequently is, "Because such and such a rule functions in thus and so way." Here are some examples:

Marxist Explanations of Law--Marxist social theory relies heavily on functionalist explanation in general, and so it is not surprising that many Marxist explanations of law are functionalist in nature. "The law is such and such, because that rule serves the interest of the capitalist class." "Feudal law governing rights in land gave way to modern property law with free alienability, because that change was required by the transition from the feudal mode of production to the capitalist mode of production."Legal Evolution
Functionalist explanations are also implicit in any claim that the law evolves (where "evolves" is meant in a technical sense and is not a mere synonym for "changes"). The idea that legal systems evolve is very common, but there is not general theory of legal evolution that has the well-confirmed status of the corresponding theory of biological evolution. Be on the watch for claims about legal evolution; such claims frequently are not well thought out and almost always lack empirical support.Efficiency
Another example of functionalist explanation in legal theory is the claim that the common law rules are efficient. "Why did the common law adopt the Learned Hand formula as the standard for negligence?" "Because that is the efficient standard." Sometimes these claims are accompanied by an account of the mechanism by which a common law system moves towards efficient legal rules. For example, it might be argued that inefficient legal rules will be subject to continuous litigation pressure; whereas efficient legal rules, once adopted, tend to facilitate settlement of disputes.

Microfoundations
When you are thinking about particular functionalist explanations in positive legal theory, it is particularly helpful to ask the question whether the explanation has "microfoundations." That is, does the functionalist explanation for a particular legal rule (or change in legal rules) incorporate a specific account of the causal mechanism by which the function caused the rule or change. It is always possible that a particular functionalist explanation is true, even if microfoundations cannot be provided, but the absence of causal mechanisms is a reason to be suspicious.
For a very lucid explanation of the role of microfoundations in social science, I highly recommend Jon Elster's brilliant book Making Sense of Marx. And for an equally brilliant defense of functionalist explanations, consult G.A. Cohen's Karl Marx's Theory of History. (The debate between Cohen and Elster is one of the most interesting and important debates in contemporary philosophy of the social science.)Conclusion
Let me conclude with a very short diatribe. Legal theorists need a basic understanding of positive legal theory. (I hope this is obvious to everyone!) That means that legal academics should, at a minimum, have a working familiarity with the general concepts of the methodology and theory of the social sciences, including basic ideas about the role of functionalist explanations. But almost no law schools (even the elite ones that train most academics) offer courses in the methodology of positive legal theory! That's bad. Real bad.